I encounter the odd issue where if I search for C# related items, like "C# enum" or "C# event handling", I get the Russian version of msdn.microsoft.com, and the sometimes the Russian version of other websites. I'm not sure if it's related, but it happens mainly when no Region has been selected.

It's not a major issue, because it's the correct page, but I always have to switch it back to English. This has happened very often recently, and there's nothing about my geographical or IP-geolocated region that would indicate Russia, nor my browser settings. I've never left the NorthEast US.

I've had the same issue sometimes even when US is set as both region and prefered language. It might have to do with the fact that the search "C#" is also found on the Russian page version. When I search C# in general the first answer I get is the Russian version of the wikipedia page.
Might have to do with "Partnership with Yandex." It is a Russian Internet Company.